Join in expert discussion on the topics of Astronomy, astrophysics and cosmology. This may include discussion on celestial objects, space, and the physical universe as a whole. Mainstream science only.
Threads
Undergrad Relationship between Energy density and Curvature
- Arman777
- · Replies 27 ·
Undergrad Opal Crystals on Mars: Implications for Geochemical Conditions
- Edge5
- · Replies 3 ·
Undergrad Sachs-Wolfe effect and Superclusters/Supervoids
- Arman777
- · Replies 7 ·
High School How Old is the Milky Way Galaxy?
- Simon Peach
- · Replies 12 ·
Graduate How do I define Open cluster membership?
- tomwilliam
- · Replies 5 ·
Undergrad Relativistic Reference Frames and the Big Bang?
- jahzam
- · Replies 6 ·
High School Is Dark Energy really the best term?
- StarTrekkin
- · Replies 7 ·
Undergrad What Are the Boundaries of a Flat and Saddle-Shaped Universe?
- msailer1234
- · Replies 24 ·
Graduate How Does Stellar Radiation Clear Dust from a Proto-Planetary Disc?
- RJ Emery
- · Replies 4 ·
High School What Mysteries Lie Between the Galaxies?
- kechloo
- · Replies 5 ·
Undergrad What are the latest thoughts about the timescape cosmology
- Arman777
- · Replies 12 ·
High School Exoplanets - Suspicious evidence and fantastical conclusions
- PaulCam
- · Replies 21 ·
Stargazing Astro Image Stacking (optimize DSS image stacking and post processing)
- Andy Resnick
- · Replies 43 ·
Undergrad Theory behind how expansion moves mass but doesn't interfere with inertia?
- Rodney-Believes
- · Replies 21 ·
Graduate Lagrangian vs pseudo-Lagrangian vs Eulerian
- SpaceNerdz
- · Replies 1 ·
High School Why didn't the Moon go fully red for this eclipse?
- swampwiz
- · Replies 8 ·
High School Is There a Reference Point for the Expansion of the Universe?
- Sarthak1221
- · Replies 3 ·
High School Comoving distance in cosmology
- Apashanka
- · Replies 1 ·
High School Hyperloop - Orbital Space Launch
- Demigod
- · Replies 28 ·
High School Earth from Space: What Would Hubble See?
- zuz
- · Replies 2 ·
High School Do Black holes reach a critical mass?
- Simon Pratt
- · Replies 3 ·
High School Could Solar Radiation Explain 'Oumuamua's Strange Trajectory?
- .Scott
- · Replies 6 ·
High School The Hubble WFC3 instrument has stopped working
- glappkaeft
- · Replies 2 ·
Undergrad Supermassive black hole eating a stellar black hole
- Joshua Guyette
- · Replies 2 ·
High School Skydiving from Space -- maximum altitude?
- neamt
- · Replies 13 ·
Graduate Hot dark matter constrained by the CMB
- fhenryco
- · Replies 7 ·
High School Missing Dark Matter of NGC1052-DF2
- wolram
- · Replies 1 ·
High School How high can a helium baloon rise to space?
- Deleted member 656102
- · Replies 18 ·
Undergrad Would it be possible to observe an alien city?
- momo666
- · Replies 6 ·
Undergrad Why does an Empty Universe have to obey Negative Curvature?
- Arman777
- · Replies 10 ·
Undergrad How to find the position of a celestial object in the sky?
- Xinran Li
- · Replies 2 ·
Undergrad What is the mass of all photons emitted in the universe?
- Louis Nardozi
- · Replies 13 ·
High School Are White Dwarves Turning into Galactic Disco Balls?
- TEFLing
- · Replies 1 ·
Undergrad What does this description mean? (two bodies orbiting each other)
- n3pix
- · Replies 4 ·
Undergrad Event Horizon and Particle Horizon
- Arman777
- · Replies 12 ·
Stargazing Astronomers discover 2nd mysterious repeating fast radio burst
- Greg Bernhardt
- · Replies 1 ·
Undergrad Solar Images Data: Where to Find?
- Phylosopher
- · Replies 6 ·
High School Further collapse of Neutron Stars
- Michaela SJ
- · Replies 4 ·
Undergrad Life on Neptune: Could Its Ocean Support Complex Life?
- sjp9220
- · Replies 5 ·
Undergrad Calculating STEVE's Height from Two Photos 370km Apart
- astroscout
- · Replies 116 ·
High School Ratio between the sizes of the Observed and the Entire Universe
- Cerenkov
- · Replies 7 ·
Undergrad Moon's eccentricity, apogee and perigee
- darkdave3000
- · Replies 13 ·
Undergrad Confusion about the math of the Comoving Coordinates
- Arman777
- · Replies 8 ·
Undergrad Formation of super-massive black holes
- Green dwarf
- · Replies 2 ·
Undergrad Is inflation needed to explain uniformity?
- Green dwarf
- · Replies 9 ·
High School Probability of our solar system colliding during Andromeda-Milky Way merger
- Glenstr
- · Replies 3 ·
Undergrad Gaia Space Telescope and Lagrangian Point 2
- Johnnyallen
- · Replies 8 ·
Undergrad Sunlight refraction at sunset at different latitudes?
- Mohsin03129
- · Replies 11 ·
Undergrad Why there is no disturbance in orbital paths?
- Kaka
- · Replies 4 ·
Undergrad Metric of the Universe and dependence on Cosmological P
- Arman777
- · Replies 7 ·
Graduate Unification of dark energy and dark matter
- Chris Ian Burkinshaw
- · Replies 1 ·
Undergrad Why Does the Sun Have an Orbital Period Like a Year?
- bunburryist
- · Replies 11 ·
Undergrad Could Our Universe Be a Mirror Image of an Antimatter Universe?
- Anthony Beckwith
- · Replies 6 ·
High School The k term in the Friedmann equation
- Apashanka
- · Replies 2 ·
Undergrad Repurposing Satellites: Maximizing the Lifespan of Space Technology
- Scott Ryals
- · Replies 6 ·
High School Ideas to protect the Earth from possible asteroid impacts
- Mlesnita Daniel
- · Replies 59 ·
Undergrad Why do we need to unify gravity with the other three forces?
- Green dwarf
- · Replies 3 ·
Undergrad The Expanding Universe and a stationary frame of reference
- darkdave3000
- · Replies 2 ·
Undergrad Footnote on page 151 of Weinberg's Cosmology book
- jouvelot
- · Replies 2 ·
Undergrad Is there any evidence of a universe expansion jerk
- arusse02
- · Replies 3 ·
Undergrad Calculating dark energy and matter density
- Ranku
- · Replies 18 ·
Undergrad Curvature of space in large regions: zero or not?
- harrylentil
- · Replies 9 ·
Undergrad Why will the Milky Way and Andromeda collide if the universe is expanding?
- Sasho Andonov
- · Replies 17 ·
High School Standard candles in a stretching fabric of space
- Rebbyte
- · Replies 3 ·
High School Galaxy Collisions & Expansion: What's Going On?
- Star32503
- · Replies 3 ·
Graduate How Long To 'FreeFall' Into TON 618 From ISCO
- Daharen
- · Replies 3 ·
High School Meaning of the Abbreviation CCH in Graphic
- Sanborn Chase
- · Replies 2 ·
Undergrad Calculating Velocity of a Ball in a Black Hole's Sphere of Influence
- alexchamp29
- · Replies 9 ·
High School The Impact of Expansion on the Observable Universe
- GraemeSRC
- · Replies 10 ·
High School Why are ds and dω taken as zero in calculating proper distance in cosmology?
- Apashanka
- · Replies 24 ·
Undergrad How does gravity vary in deep mines and interstellar gas?
- KurtLudwig
- · Replies 6 ·
High School Discover 4 Milky Way Arms: Older Galaxies?
- TEFLing
- · Replies 10 ·
Undergrad Do trojan satellites follow migrating planets?
- harrylentil
- · Replies 16 ·
High School Space Time fabric graphic is misleading
- megacal
- · Replies 4 ·
Stargazing Best Telescopes for $1K: Mars, Planets & Night Sky Views
- LightMatters
- · Replies 12 ·
High School Water - Where do you think it came from?
- Kay Marie
- · Replies 5 ·
Stargazing Australia's largest optical telescope
- davenn
- · Replies 3 ·
High School Searching for the Ninth Planet: Solar System Migration
- wolram
- · Replies 5 ·
Undergrad Why do transits of Mercury only occur in May & November?
- swampwiz
- · Replies 4 ·
High School Interstellar Dust: What Blocks Light From Distant Galaxys?
- zuz
- · Replies 15 ·
Undergrad Expansion of 3-D positively curved space
- Apashanka
- · Replies 4 ·
Undergrad Black holes with a naked singularity?
- bbbl67
- · Replies 7 ·
High School Why most stars seem to rotate the same direction in a galaxy?
- fbs7
- · Replies 6 ·
Undergrad Is there a mechanism for creation of negative energy density
- Christofer Br
- · Replies 2 ·
Undergrad What is the energy density of spacetime?
- KurtLudwig
- · Replies 20 ·
High School Why doesn't the moon fall down if it's just a big rock?
- rootone
- · Replies 9 ·
Graduate Is there any astro-field that uses QM or GR frequently?
- physicist91
- · Replies 1 ·
High School Question regarding if curvature is not constant
- Apashanka
- · Replies 6 ·
Undergrad Legendre polynomials in boosted temperature approximation
- jouvelot
- · Replies 8 ·
High School Positive curvature of a 2D surface
- Apashanka
- · Replies 24 ·
Undergrad If a planet struck the sun, would fragments be blasted out?
- Edward Barrow
- · Replies 7 ·
High School Dark matter research paper question
- LailaR
- · Replies 8 ·
Undergrad Are there issues with Conformal Gravity as a DM solution?
- ohwilleke
- · Replies 5 ·
High School Parallax Limitations: Measuring Distances Miles Away
- nmsurobert
- · Replies 4 ·
Undergrad Total number density of galaxies and problematic expression
- fab13
- · Replies 15 ·
Undergrad Infer the distance of a closest neighbor galaxy from correlation
- fab13
- · Replies 9 ·
Undergrad Why isn't Mercury as red as Mars, even though it has more iron?
- bbbl67
- · Replies 9 ·
Undergrad Would an exploded planet change earths orbit (see graphic)
- Edward Barrow
- · Replies 12 ·
Stargazing What is the best Dobsonian telescope with a goto feature?
- PEGELLA
- · Replies 13 ·
Undergrad What factors determine the composition of a planet's atmosphere?
- Drakkith
- · Replies 4 ·